1. Field of the Invention
The present invention relates to a medical tube and a flexibility-variable mechanism.
2. Description of the Related Art
Japanese National Phase Patent Laid-Open Publication No. 2007-511247 discloses a flexibility/rigidity-variable device that includes a tube which is an elongated member, a projection (engaging abutment) provided on the outer circumference of the tube, an engaging portion which is engageable with the projection, a sealing cover that covers the outer circumference of the tube, and a fluid inlet/outlet portion connected to a sealed space between the sealing cover and the tube. This reference describes a medical tube in which, when the air within the sealed space is discharged from the inlet/outlet portion to the outside, the engaging portion may be engaged with the projection of the tube and the shape of the tube may remain in a fixed state.
Japanese National Phase Patent Laid-Open Publication No. 1994-511163 discloses a medical tube in which a main body to be inserted into the inside of a patient's body has a deflectable or steerable shaft, and the shaft is provided with a plurality of elements which may be engaged with each other. This reference describes that each element is provided with, for example, a lumen through which a pull wire extends and a scope lumen at the center thereof, and when a tension is applied to the pull wire, the elements are pressed so that the shaft may be fixed at a predetermined position.
Japanese National Phase Patent Laid-Open Publication No. 2009-107792 discloses a flexibility-adjustable exploration device having an inner duct and an outer duct. This reference describes that the inner duct is configured by a plurality of cylindrical segments which are connected in series and bound by a flexible cable. Further, this reference describes that, when elasticity is given to the cable, the respective segments are fixed and not to be moved by frictional force.
However, the first two references have a problem in that because the shaft or the inner duct is fixed using a wire, the diameter of a portion to be inserted into a patient's body is increased.
For flexibility of a medical tube, it is necessary to control the medical tube such that the medical tube is in a fixed state in which it is somewhat flexible depending on a medical treatment portion. However, the medical tubes described in the first two references have a problem in that it is impossible to control the medical tubes to be in such a fixed state.
In addition, the third reference has a problem in that because a high rigid support member is provided along the longitudinal direction of the tube, the flexibility varies depending on the curved (bent) direction of the tube. That is, the ducts disclosed in this reference have a problem regarding anisotropy in terms of flexibility.